The overall reported costs for official&nbsp; travel abroad by Members of Congress dipped slightly last year, with House and Senate committees and delegations publicly reporting they spent $10.1 million, though that figure is a fraction of what the trips actually cost taxpayers.

According to travel disclosures published in the Congressional Record, the federal government spent $4.9 million on trips overseas for Representatives and their staffers and $5.2 million for Senators and their staffers in 2011. The year before, the Senate reported roughly the same amount and the House reported just more than $5 million, according to a Roll Call tally of costs reported in the Congressional Record.

The Senate discloses travel for all committees in a single report each quarter, making it relatively easy to determine the total cost of such trips. In the House, however, each committee and delegation publishes its own report, making it more difficult to assemble a tally for the year.

Figuring the overall cost of Congressional travel overseas is further complicated by the fact that only a fraction of the costs associated with the trips are accounted for in the committee and delegation reports. Expenses that show up in the Congressional Record typically cover commercial airfare and per diems used for on-the-ground costs such as meals and lodging. Those funds come out of a bottomless account at the Treasury Department that doesn&rsquo;t require Congressional appropriations. But as Roll Call has previously reported, the Pentagon and the State Department spend millions of dollars more on government aircraft and logistical arrangements that are not listed on the committee and delegation reports.

Reports published by the Treasury Department on the account that the State Department uses to pay for Congressional travel costs show just how quickly the costs can increase. One Treasury report said the government spent $110.5 million on Congressional foreign travel from 2001 through 2009, which is $30 million to $40 million more than what was reported in the Congressional Record during the same period.

Some trips make it clear just how much spending goes undisclosed. When the House Budget Committee sent Rep Rob Woodall (R-Ga.) on a six-day trip to Kuwait, Iraq, Pakistan, Afghanistan and Germany in June, it reported spending only $664 in per diem expenses from the special travel account while the other costs were presumably covered by the military or the State Department.

When Rep. Randy Forbes (R-Va.) joined a seven-day delegation led by Sen. James Inhofe (R-Okla.) to Burkina Faso, Uganda, Ethiopia, Djibouti, Israel, Turkey and Germany in February 2011, the Armed Services Committee reported spending only $42 from the bottomless travel account.

Some committees report higher travel costs than others.

The House Intelligence Committee reported spending the most on foreign travel in a single quarter. From April 1 to June 30 of last year, the committee reported it spent $371,000 to send its Members and staffers to locations in Southeast Asia, the Middle East, Africa and Europe. More detailed information about the committee&rsquo;s travel locations is not reported because of the sensitive nature of its work.

During the same quarter, the House Foreign Affairs Committee reported spending $316,000 from the bottomless Treasury Department account on trips abroad. Its Members and staffers traveled to Russia, Portugal, Italy, Georgia, Lithuania, Israel, Haiti and Afghanistan, among other locations.

In the Senate, the most expensive quarterly travel report was filed by the Foreign Relations Committee for trips taken during the first quarter of last year.

From January to March, its Senators and their staffers traveled to Colombia, Brazil, Panama, Chile, Sudan, Japan, Egypt and Tunisia, among other locations.

The drop in Treasury Department funds spent on Congressional travel comes at a time when the amount that private groups spend on Congressional travel is rapidly increasing.

As Roll Call reported in January, private organizations spent almost $6 million sending Members of Congress and their staffers on trips last year, a nearly $2.5 million increase from 2010 and more than in any year since Congress tightened its restrictions on outside groups paying for travel in 2007.